<template>
  <div>
    <ul>
      <li v-for="(item,index) in arr" :key="index">
      {{item.name}}
      <button @click="fn(index)">买书</button>
      </li>
    </ul>
    <table border="1" width="500" cellspacing="0">
      <tr>
        <th>序号</th>
        <th>书名</th>
        <th>单价</th>
        <th>数量</th>
        <th>合计</th>
      </tr>
      <tr v-for="(item,index) in arr" :key="index">
       <td>{{index+1}}</td>
       <td>{{item.name}}</td>
       <td>{{item.price}}</td>
       <td>{{item.count}}</td>
       <td>{{item.price*item.count}}</td>
      </tr>
    </table>

    <p>总价格为：{{con}}</p>
  </div>
</template>

<script>
export default {
  computed:{
con(){
  return this.arr.reduce((sum,item)=>sum+item.count*item.price,0)
}
  },
data () {
  return {
    arr: [
        {
          name: "水浒传",
          price: 107,
          count: 0,
        },
        {
          name: "西游记",
          price: 192,
          count: 0,
        },
        {
          name: "三国演义",
          price: 219,
          count: 0,
        },
        {
          name: "红楼梦",
          price: 178,
          count: 0,
        },
      ],
  }
},
methods:{
  fn(ind){
  this.arr[ind].count=this.arr[ind].count+1
   
  }
}
}
</script>

<style>

</style>